Did you set Telemetry to 0 (or used tools to remove Telemetry)? With Telemetry level 0, you won't get offered the CUs through WU. However, you can still install them offline (using WSUS Offline Update / or WUMT in offline mode, together with wsusscn2.cab).
Check the registry key Code: Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\DataCollection if the "AllowTelemetry" value is set to 0. If it is, you might not get CUs the normal way. Various "privacy" tools for stopping MS data collection set that value to 0.
1. set active hours 2. set work wifi as metered by this way you should be installing regular updates only when free. Tweaking telemetry should only be done when you know what you are doing.
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\DataCollection Telemetry should be 3